Exactly what it sounds like. The
red-
purple sputum that is a mixture of cranberry pulp and the excess mucus caused by irritation from drinking the acidic juice. Similar substances can come out of drinking lemon or
grapefruit juice, but those tend to be a less alarming and therefore noteworthy color.
"
Holy shit, did you just cough up blood?!"
"No, that's just cranberry flem; I
drank some cranberry juice earlier"
"Oh...
Gross"